Electrical connector cap



March 1, 1966 J HEALY 3,238,493

ELECTRICAL CONNECTOR CAP Filed April 4. 1963 United States Patent 3,238,493 ELECTRICAL CONNECTOR CAP Joseph F. Healy, deceased, late of Westport, Conn, by

Beatrice M. Healy, administratrix, Westport, Conn., assignor to Harvey Hnbbell Incorporated, Bridgeport, Conn, a corporation of Connecticut Filed Apr. 4, 1963, Ser. No. 270,767 Claims. (Cl. 339103) This invention relates to an improved electrical wiring device and, more particularly, to a connector cap of the explosion-proof type.

Explosion-proof electrical connector caps are commonly used in hazardous locations where they are exposed, in addition to explosive elements and inflammable elements, to dirt, moisture and soilage. In such locations, fast action is often required in connecting or disconnecting the plug. One example of such a location is in a hospital operating room, where it is necessary to electrically power appliances in an atmosphere of explosive and inflammable elements where soilage is present that can contaminate the connector cap and require its cleaning.

As in all heavy-duty wiring apparatus, it is important in explosion-proof connector caps that the electrical cord wired to the cap be firmly secured to the body of the cap to prevent the electrical wiring connections from being loosened. In prior art apparatus, this has been accomplished by externally located cord clamps positioned on an end of the casing of the cap. These prior art cord clamps are not only unsightly, but also hazardous because of the possibility of their snagging on clothing or cutting or scratching the hands of a user, which is particularly highly undesirable in a hospital operating room.

For hospital operating room use and for certain other applications it is also desirable to provide a cap which can be easily cleaned or sterilized in a liquid solution and then rapidly put back into service. All of these desirable attributes are missing from prior art caps, many of which require complete disassembly in order that they may be properly cleaned, and all of which require external cord clamps.

Accordingly, it is a primary object of this invention to provide an improved explosion-proof electrical cap possessing all of these attributes. Other more specific objects are to provide such a cap which has an enclosed cord grip and which can be directly contacted with a liquid cleaning solution and placed back into service with a minimum of delay. Other objects, features and advantages will be apparent from the following description, the appended claims, and the figures of the attached drawing, wherein:

FIG. 1 is a side elevational view of an electrical connector cap which incorporates the invention, with portions cut away and shown in section to show the internal construction;

FIG. 2 is a sectional view taken substantially along the line 2--2 of FIG. 1;

FIG. 3 is a right end view of the cap of FIG. 1; and

FIG. -4 is an exploded view of the cord clamping means of the invention.

The illustrated cap is generally cylindrical and of the bayonet type having a grounding terminal. However, the invention is equally adapted for use with any type of electrical cap. In FIG. 1, the connecting portion of the cap is illustrated as comprising a central bayonet post 18 of a rigid electrical insulating material, such as a suitable plastic, as a phenolic resin, which carries a grounding contact 12 and two line contacts 14, for selective connection in a known manner with contacts of an electrical receptacle. The bayonet post 10 is integrally formed with a cylindrical flange 16, and an integrally formed projection on the opposite side of the flange carries wiring 3,238,493 Patented Mar. 1, 1966 terminal clamps 17 for connecting the line and grounding wires 18 of the electrical cord 38 to the proper external contacts 12, 14.

Surrounding the wiring zone is a cylindrical wiring enclosure 20 which is also formed of a rigid insulating plas tic, such as a phenolic resin. The right end of the wiring enclosure 20 adjoins the cylindrical flange 16 and may be keyed thereto by means of a projection in one member and a recess on the other to assist in alignment. The wall of the enclosure 20 includes a pair of spaced longitudinally extending passages 22. The left end of the enclosure 2% includes a radially inwardly sloping annular shoulder 24 which defines a central opening symmetrically positioned relative to the longitudinal axis of the enclosure. Disposed within the opening defined by shoulder 24 is an inner resilient sealing bushing 26 which is substantially cylindrical and has an outer radial flange 28 which rests against the outer end surface of the wiring enclosure 20.

The main casing for the explosion-proof cap of the invention is a metal cylinder 30 open at its right end to snugly receive the cylindrical flange 16 of the bayonet post 10, and partially enclosed at its left end by a radially inwardly extending annular wall 31 to form a central opening of reduced diameter defined by an outwardly sloping hub-like shoulder 32. Disposed within the shoulder 32 is an outer sealing bushing 34 which is similar to bushing 26 and, as the inner bushing, includes a flange 36. Bushing 34 is reversed relative to bushing 26 so that its flange 36 is inside cylinder 30 while the cylindrical portion extends through the opening formed by shoulder 32. The inner bushing 26 and the outer bushing 34 are both made of a resilient material, such as rubber. In the assembled cap, as illustrated in FIG. 1, each of a pair of bushings 26, 34 encircles a flexible electrical line cord 38 which includes the conductor wires 18.

Against the inner surface of the flange 36 of outer sealing bushing 34 there is positioned an annular metal washer 40. Between washer 4t) and the flange 28 of inner bushing 26 there are positioned a pair of generally similar cord clamps 42 which are most clearly illustrated in FIG. 4. Each of the cord clamps 42 includes a partially cylindrical section which contacts the periphery of the cord 38. The cord clamps are mounted at opposite sides of the cord. Each of the clamps also includes a pair of oppositely outwardly projecting cars 44. The cars of opposing pairs face one another and are suitably apertured to receive machine screws 46 which are arranged to tighten the clamps on the cord 38 to effect a strain relief. Each of the cord clamps 42 also includes a pair of diverging generally radially extending arms 48 at each axial side of its partial cylindrical section which lie in planes parallel to each other and perpendicular to the longitudinal axis of the cord. The arms 48 which are positioned toward the inner portion of the cap abut the flange 28 of the inner sealing bushing 26 and the arms nearest shoulder 32 abut the washer 40, which bears against the flange 36 of outer sealing bushing 34.

The entire cap assembly is held together by means of screws 50, which have their heads disposed in recesses in the front face of cylindrical flange 16 and extend longitudinally therethrough and of the passages 22 in enclosure 20 into elongated internally tapped sleeves 52. Sleeves 52 are riveted or otherwise rigidly secured at their left ends to the wall 31 of metal body 30 and extend into the longitudinal passages 22 provided in the enclosure 20. The outer surface of the metal body 30 is provided with inwardly extending indentations 54 which form shoulders on its inner surface against which bears the inner end of the wiring enclosure 20 to position the latter.

R is believed that the operation and advantages of the invention can be best understood by considering the mode of assembly of the cap. In assembling this cap, the metal cylinder 30 is first pushed on the end of the electrical line cord 38. The outer sealing bushing 34, the washer 40 and the inner sealing bushing 26 are also pushed on the cord. The wiring enclosure 20 is next pushed on the cord, and the wires 18 of the cord are then connected to the proper terminals 17 on the inner side of the cylindrical flange 16. The wiring enclosure 20 is then positioned adjacent to the flange 16 and the inner sealing bushing 26 is moved on the cord 38 to a position closely adjacent the shoulder 24 on the wiring enclosure so as to extend through the opening formed by the shoulder. The cord clamps 4-2 are then placed against opposite sides of cord 33 with some of their arms 48 adjacent the flange 28 of bushing 26 and the screws 46 are tightened so as to draw the clamps together and clamp the cord tightly. The washer 40 and the outer sealing bushing 36 are then moved on the cord until they are adjacent the arms 48 at the outer sides of cord clamps 42. The cylinder 30 is then moved on the cord into position to enclose the entire assembly, as illustrated in FIG. 1. During such movement of the cylinder the end of the outer sealing bushing 34 is forced into the opening defined by the inclined shoulder 32. Screws 50 are then inserted through the flange 16 and into the sleeves 52 and are tightened. The tightening of screws 50 forces the flange 16 and the wiring enclosure 20 together, and the enclosure shoulder -24 against the inner surface of the flange 28 of the sealing bushing 26 to form a seal therewith. Another seal is formed between the main body of the bushing 26 and the slanted surface of shoulder 24. Tightening of screws 50 also forces the flange 28 against the anms 48 at the inner sides of clamps 42, and the flange 36 of the outer bushing 34 against the washer 40. Washer 40 distributes the pressure of the arms 48 evenly on flange 36. The outer bushing 34, therefore, serves to seal the clamping zone against the entry of dirt and moisture. At the same time, the inner bushing 26 isolates and seals the cord clamping zone of the cap from the wiring zone of the cap.

Although the foregoing results in a fully assembled cap, the final step in producing a commercially acceptable explosion-proof cap is to pot the wiring zone with a suitable potting resin which may be introduced into the cap through appropriate openings provided in flange 16. The technique of potting is well known to those skilled in the art, and therefore, will not be specifically described herein. After potting, the entire wiring zone is filled with a solid mass of hardened resin which encapsulates the terminals 17 and leads of wires 18.

The completed cap not only presents a streamlined appearance, but is free of any projections which might he accidentally snagged by hands or clothing. Further, the cap is completely waterproof and in use may even be sterilized and placed back immediately into service by merely wiping moisture or soilage off its external parts.

It will be apparent to those skilled in the art that the cap of this invention provides a number of significant advantages over prior art devices. It will also be apparent that a number of modifications and variations may be made therein Without departing from the spirit and scope of the invention. Accordingly, the foregoing description is to be construed as illustrative only, rather than limiting. The invention is limited only by the scope of the following claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In an electrical wiring device conne-cta'ole to an electric cord and including a casing defining an opening for said cord, electrical connector means, and means for wiring said connector means to the conductors of said cord, the improvement which comprises: cord clamping means positioned entirely within said casing and arranged to grippingly engage said electric cord to effect a strain relief; resilient sealing means encircling said cord adjacent the inner side of said opening; a compression member telescopically slidably mounted within said casing for forcibly compressing said sealing means between said casing and said cord clamping means; and means for selectively advancing said member toward said cord clamping means whereby said opening is sealed around said cord.

2. The device of claim 1 wherein said casing and compression member are substantially cylindrical.

3. The device of claim 1 wherein said advancing means comprises screw means connecting said member and said casing.

4. The device of claim 1 wherein said cord clamping means comprises radially extending arms lying in a plane erpendicular to the longitudinal axis of said casing and positioned to compress said sealing means.

5. The device of claim 1 wherein resilient inner sealing means is positioned between said member and said cord clamping means.

6. The device of claim 5 wherein said resilient inner sealing means comprises a generally cylindrical bushing encircling said cord and disposed between and adjacent said member and said cord clamping means.

7. The device of claim 6 wherein said cord clamping means comprises a pair of clamps, each of which includes radially extending arms, some of said arms contacting said inner sealing means and some arranged to compress said sealing means.

8. The device of claim 7 wherein a rigid washer is disposed on said cord between and in contact with said sealing means and some of said arms.

9. An explosion-proof cord connector cap comprising a casing having an end opening; means defining a wiring Zone within said casing; means defining a cord clamping zone within said casing; a wall having an opening separating said zones; a cord extending through said openings; a separate sealing bushing adjacent each of the openings; and cord clamping means mounted on said cord to clamp it and effect a strain relief and including means for compressing said bushings to form seals at the openings.

10. The cap of claim 9 wherein said cord clamping means comprises a pair of generally similar clamps, each of which includes a partial cylindrical section for contacting said cord and radially extending arms to compress said bushings.

References Cited by the Examiner UNITED STATES PATENTS 2,686,828 8/1954 Guy et a1. 339l03 X 2,972,004 2/1961 Merrell et al. 17493 X 3,121,600 2/1964 Healy 339103 JOSEPH D. SEERS, Primary Examiner.

W. DONALD MILLER, Examiner. 

9. AN EXPLOSION-PROOF CORD CONNECTOR CAP COMPRISING A CASING HAVING AN END OPENING; MEANS DEFINING A WIRING ZONE WITHIN SAID CASING; MEANS DEFINING A CORD CLAMPING ZONE WITHIN SAID CASING; A WALL HAVING AN OPENING SEPARATING SAID ZONES; A CORD EXTENDING THROUGH SAID OPENINGS; A SEPARATE SEALING BUSHING ADJACENT EACH OF THE OPENINGS; AN CORD CLAMPING MEANS MOUNTED ON SAID CORD TO CLAMP IT AND EFFECT A STRAIN RELIEF AND INCLUDING MEANS FOR COMPRESSING SAID BUSHINGS TO FORM SEALS AT THE OPENINGS. 